A fermentation process whereby lactic acid is synthesized by fermentation caused by lactic acid bacteria, ammonium lactate is obtained therefrom, and a lactic acid ester is then produced is known as a method for producing a lactic acid ester (JP Patent Publication (Unexamined) Nos. 2004-208501, 2002-300898, 7-194387 (1995), and 2003-284580). In this method, lactic acid produced by fermentation is neutralized with ammonia to prepare ammonium lactate, and alcohol is added thereto to esterify the ammonium lactate. Also, sulfuric acid is added to the reaction system to promote the esterification reaction. In such a production method, a lactic acid ester contained in the reaction solution is isolated by distillation and recovered at the end of the process.
Conventional methods for producing a lactic acid ester, such as those disclosed in the above patent documents, do not provide techniques that are sufficient to industrially produce a lactic acid ester. These methods have not been practical in terms of production cost. Specifically, the industrial production of a lactic acid ester requires a minimization of input energy at the time of production, a reduction in chemical costs, and a minimization of equipment costs. However, conventional methods for producing a lactic acid ester have not been able to provide any concrete means of fulfilling such requirements.